Possible way to record DirecTV? - AVS Forum
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Old 07-20-2001, 07:38 AM - Thread Starter
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Hi.

I'm a newbie to this forum. But I am amazed at the kinds of things I see that people are doing with their home theater systems. I didn't realize so may folks were on the cutting edge of HDTV.

Here's an HDTV recording idea I'm trying to work the bugs out of.

Has anyone used a product that converts the component outputs of a HD set top box into a IEEE 1394 DV stream? If so, wouldn't that firewire stream be compatible with with the Panny PV-HD1000, the JVC HM-DH30000, or the new Mitsubishi coming out?

I ran across a product that does something kind of like that, the Laird Telemedia LTM-5500.
http://www.lairdtelemedia.com/products/firewire.html

I know it says that it is for NTSC, but has anyone tried it with HDTV? Or is there a similar product out there does this for HDTV? I'm aware that there would be some signal loss, but it should be minor. Given that capturing an NTSC signal with DV is practically identical to the source material.

In fact, if a solution like this is out there I wouldn't be suprised if it surpasses the quality of a W-VHS unit.

Any suggestions?
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Old 07-20-2001, 09:49 AM
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I gave this a lot of thought a year ago and concluded that even if the Laird unit could (doubtful) pass the HD bit-stream rate, there was still the issue of not being able to record the 5.1 DD audio.
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Old 07-20-2001, 11:21 AM
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Don't know much about it, but it seems feasable if you do not care about the 5.1. In fact I notice a lot of PPV HDTV is only 2.0 anyway.

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Old 07-20-2001, 11:31 AM
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No. this will not work. First the device you specify does not work at HD rates. Second, you need to understand "firewire" or 1394 interfaces. The 1394 specification is an ELECTRICAL specification. It also includes some low level command structures as well. But it says nothing about the data or formatting over the interface. The PVHD1000 used 1394 because it was a good choice for the data rate needed. Camcorders use this interface to and from editing software. But these standards are not the same when it comes to the data being passed over the interface.

It's kinda like saying this telephone is compatable with any service in the USA. It will work in any standard analog jack. That does not mean however the person on the other end speaks english.

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Old 07-20-2001, 11:58 AM - Thread Starter
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Thanks for the input.

Then has anyone out ther made some kind of converter box to handle this issue?

There are boxes that do it for NTSC. Such as the Sony DVMC-DA2 and DVMC-MS1. Also this box by Fastware. http://www.fastware.net/a0800/dvp1.html

Does anyone make one for HDTV?

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Old 07-20-2001, 01:26 PM
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I hate to say it, but the 169 Time approach is probably the most doable... Too bad they can't get to work. http://www.avsforum.com/ubb/frown.gif

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Old 07-20-2001, 01:51 PM
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Quote:
Originally posted by Glimmie:
The 1394 specification is an ELECTRICAL specification.
FireWire is much more than an electrical specification. It says quite a bit about modulation, addressing, logical, and network-level specifications.

The payload, however, is arbitrary. The format of the payload is up to the devices.

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Old 07-20-2001, 03:40 PM
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Does this imply that, in theory, a DVHS machine could be hooked up to a PC via a *standard* Firewire card, if you understood the proper protocols, handshaking, etc?

Put another way, Assuming there are APIs available on the PC end to send/receive low-level commands on the Firewire port (device select, etc), is this sufficient to write a program to talk to a DVHS machine? (Again, assuming you understand the command set for the DVHS machine)

And lastly, given that (I believe) its been proven that the JVC 30000 and the Panasonic 1000 DVHS machines are able to talk to one another (to make tape duplicates), doesnt this imply that the command set specification is non-proprietary, and available for the price of a specbook?

Andy K.
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Old 07-20-2001, 08:47 PM
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Andy,

Yes, I believe it could be done rather easily, particularly with the PV-HD1000 recorder. In my experiments using a hub with these devices it is apparent that the HD1000 does very little in the way of control or checking of incoming firewire signal. Just hit record and it happily swallows up the isochronous bitstream.

All these devices follow the IEEE1394 specifications, and there is an A/V section to the specs. I found a good book on the topic, but it's at home. I'll post the name later.

Another good example of this is the communication between the JVC DH30000, and the HD1000. For simple dubbing between the two, where the only concern is the isochonous bitstream, they work well together. But if you try to make the DH30000 work with a Panny STB there are problems, because they don't communicate well at the asynchonous level.

Here the book. "Firewire System Architecture, Second Edition" by Don Anderson. Published by Addison Wesley.

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Old 07-21-2001, 12:11 AM
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With all the other reasons that it wouldn't work, also add that it would not be a good solution because you would be working with an analog signal not the underlying digital signal. You would start having generational signal losses as you record and playback. The right thing to do is to find a way to digital record the original MPEG2 datastream. Too bad 169time seems to have self destructed before they got their act together (and that is putting it nicely).
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Old 07-21-2001, 01:29 AM
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I just got a DST50 for $199. It would be great to able to firewire it onto a PC.

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Old 07-21-2001, 05:49 AM - Thread Starter
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Speaking of 169time.

Did anyone ever get there hands on even one working product? Or was it all just vaporware all along?

If there are some working models out there, why doesn't someone just copy the design and pick up where they left off? Sounds like they are a doomed company anyway.
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Old 07-21-2001, 07:35 AM
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Quote:
Originally posted by kelliot:
I just got a DST50 for $199. It would be great to able to firewire it onto a PC.
I'd be happy with any sort of communication between the two. If the DST50/1 thinks its talking to a DVHS it will output its iso bitstream, and that can be shared by other devices using a hub. Even if the PC couldn't successfully record the bitstream it could still be "master" of a group of DVHS recorders, alowing multiple recording windows, sequential tapes of events, etc.

On the other hand, it the PC can be made to act like a nondescriminating data recorder, much like the HD1000, then, even if the PC couldn't talk the control/status language of the DST50/1 it could still "snoop" the bitstream while the STB was yaking with a DVHS recorder.

Sorry, guess I'm thinking out loud.http://www.avsforum.com/ubb/smile.gif Doesn't help the DirecTV problem either.

Nice price on the 50, Ken.

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Old 07-25-2001, 11:28 PM
 
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qoute.."i got a 50 for $199"

Wow. I paid $800 for a floor sample at best buy@@!
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